The invention relates to a rotary hammer with a tool holder provided at the front end for a drilling and/or chiselling bit which is drivable by a rotary drive to produce a rotary movement of the drilling and/or chiselling bit, with a hammer mechanism for transmitting impact energy onto the drilling and/or chiselling bit, which hammer mechanism is couplable via a coupling to a rotatingly driven intermediate shaft, and with a switching device for switching between pure drilling operation, rotary hammering operation and pure hammering operation, which switching device has a single actuator to be operated by the user for switching between drilling, rotary hammering and hammering operation as well as a cam part which is untwistable relative to the actuator and a slide part for the axial shifting of a toothed wheel, which are coupled to the actuator, wherein, in the position for pure drilling, the cam part keeps the coupling disengaged and wherein, in a first position, the slide part keeps the toothed wheel in the position for the rotary driving of the tool holder and, in a second position, keeps it in the position in which no rotary driving of the tool holder takes place.
With a known rotary hammer of this type (EP 0 454 348 B1) there is attached to the actuator on one side a cam part which has an arcuate cam surface which lies with its circle centre point concentric relative to the axis of rotation of the actuator and which, in one position of the cam part and thus of the actuator, prevents the coupling for the activation of the hammer mechanism from being brought into engagement by pressing the drilling and/or chiselling bit located in the tool holder against the workpiece, i.e. pure drilling operation results in this position. On the other hand, a guide curve is formed in the actuator which, in all positions, is engaged by a forked area of a slide part. As a result of this engagement, when the guide curve is displaced as a result of twisting of the actuator, the guide curve effects a corresponding displacement of the slide part. This engages with an axially displaceable toothed wheel arranged on the spindle of the rotary hammer and shifts it so that, in the aforementioned position of the cam part in which the coupling for the drive of the hammer mechanism cannot be brought into engagement, it meshes with a toothed wheel on a driven intermediate shaft, which results in the position for pure drilling operation. This meshing engagement also exists in the position for rotary hammering operation in which the coupling can be brought into engagement due to a correspondingly twisted position of the cam part, whereas for pure chiselling operation the slide part moves the toothed wheel mounted on the spindle out of engagement with the toothed wheel of the driven intermediate shaft, while the position of the cam part permits the engagement of the coupling and thus the activation of the hammer mechanism.
This known rotary hammer thus permits switching between pure drilling operation, rotary hammering operation and pure hammering operation by means of a single actuator to be operated by the user, but has relatively large dimensions because of the shape of the guide curve. In addition the engagement between the guide curve and the forked section of the slide part may cause some difficulty in movability or even a blockage, so that problems result when switching.